Math Problem Statement

Form a polynomial f left parenthesis x right parenthesis with real coefficients having the given degree and zeros. Degree​ 4; ​ zeros: 3 minus 4 i ; minus 2 multiplicity 2

Solution

To construct a polynomial with real coefficients, we need to use the given information:

  • Degree 4: The polynomial will have 4 roots (including multiplicities).
  • Zeros:
    • 34i3 - 4i: Since the coefficients must be real, the complex conjugate 3+4i3 + 4i is also a zero.
    • 2-2 with multiplicity 2: This means the factor (x+2)(x + 2) appears twice.

Step-by-step construction:

  1. Form factors for the zeros:

    • For the complex conjugate pair 34i3 - 4i and 3+4i3 + 4i: (x(34i))(x(3+4i))\left( x - (3 - 4i) \right) \left( x - (3 + 4i) \right) Use the difference of squares formula: (x3)2+16=x26x+25\left( x - 3 \right)^2 + 16 = x^2 - 6x + 25

    • For the zero 2-2 with multiplicity 2: (x+2)2=x2+4x+4(x + 2)^2 = x^2 + 4x + 4

  2. Form the polynomial: Multiply the two factors: f(x)=(x26x+25)(x2+4x+4)f(x) = \left( x^2 - 6x + 25 \right) \left( x^2 + 4x + 4 \right)

  3. Expand the product: Use distribution (multiplying every term in one factor by every term in the other):

    f(x)=x4+4x3+4x26x324x224x+25x2+100x+100f(x) = x^4 + 4x^3 + 4x^2 - 6x^3 - 24x^2 - 24x + 25x^2 + 100x + 100

    Now, combine like terms: f(x)=x42x3+5x2+76x+100f(x) = x^4 - 2x^3 + 5x^2 + 76x + 100

Thus, the polynomial is: f(x)=x42x3+5x2+76x+100f(x) = x^4 - 2x^3 + 5x^2 + 76x + 100


Do you have any questions or need more details?

Here are 5 related questions:

  1. How do you find the complex conjugate of a given complex number?
  2. What is the difference of squares formula and when is it used?
  3. How do multiplicities affect the shape of a polynomial’s graph?
  4. What is the fundamental theorem of algebra?
  5. How do you determine the degree of a polynomial?

Tip: Multiplying complex conjugate pairs always gives a quadratic expression with real coefficients.

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Math Problem Analysis

Mathematical Concepts

Polynomial Equations
Complex Numbers
Real Coefficients
Multiplicity

Formulas

Difference of Squares Formula
(x - (a + bi))(x - (a - bi)) = (x - a)^2 + b^2

Theorems

Fundamental Theorem of Algebra

Suitable Grade Level

Grades 10-12